Oxygen isotope ratio of leaf and grain material correlates with stomatal conductance and grain yield in irrigated wheat

Theory (Craig and Gordon 1965; Dongmann et al. 1974; Sternberg et al. 1986; Farquhar and Lloyd 1993) suggests that the oxygen isotope ratio (d 18 O) of plant material should reflect the evaporative conditions under which the material was formed, so that differences in stomatal conductance should show up in plant d 18 O. To test this theory we measured the oxygen isotope ratio of organic matter from flag leaves at anthesis and grain at harvest...